You should alsoinstall the Windows 8.1 SDK to the default install location.

Run set DEPOT_TOOLS_WIN_TOOLCHAIN=0, or set that variable in your global environment.

Visual Studio Express is not supported and will not be able to build Chromium.

Compilation is done through ninja, not Visual Studio.

Google employees

Run: download_from_google_storage --config and follow the authentication instructions. Note that you must authenticate with your @google.com credentials, not @chromium.org. Enter "0" if asked for a project-id.

Once you've done this, the toolchain will be installed automatically for you in Step 3, below (near the end of the step).

The toolchain will be in depot_tools\win_toolchain, and windbg can be found in depot_tools\win_toolchain\vs2013_files\win8sdk\Debuggers.

If you want the IDE for debugging and editing, you will need to install it separately, but this is optional and not needed to build Chromium.

If you're primarily going to be doing debug dev builds, you'll want to set GYP_DEFINES=component=shared_library, which uses a DLL build and incremental linking, which makes linking much faster in Debug.